Make no mistake, the Air Force doesn't want to use Russian-made rocket engines, a top general said Friday.

"The DoD is absolutely committed to transitioning off the RD-180. There should be no doubt," said Lt. Gen. Samuel Greaves, the commander of the Air Force Space and Missile Systems Center.

The Russian-made RD-180 engines are currently being used by United Launch Alliance, a joint Boeing-Lockheed Martin organization that has many of the defense contracts for launching U.S. military satellites and equipment into space.

Some members of Congress, led by Sen. John McCain, R-Ariz., don't want the Air Force relying on a company that needs the Russian engines to reach space, and have debated introducing legislation into the defense budget that would limit how many engines the company could buy for military launches.

But Air Force leaders have said that stopping use of the RD-180 immediately would hamper American access to space, and that the U.S. needs to keep using the engines until replacements are made.

"Launch services using non-allied engines…will be replaced with new systems as they become certified," Greaves told a breakfast hosted by the Air Force Association's Mitchell Institute for Aerospace Studies.

He noted that the Space X Falcon 9 rocket has already been certified for military launches, and will likely compete with ULA's Atlas V and Delta IV rockets for launch contracts. Other groups such as Blue Origin and Aerojet Rocketdyne are also working on rockets of their own.

"After all the systems are developed, somewhere between 2022 and 2023, we'll transition to a strategy of sustained competition where assured access to space is obtained by leveraging the domestic launches  of at least two commercially viable launch services," Greaves said.

The Pentagon is relying on "innovative public-private partnerships," the general said. The earlier in the rocket-designing process that businesses and the military can work together, the cheaper it usually is to make sure the rockets meet Pentagon standards for defense launches.

"Launch systems solely designed for commercial systems may not meet national security launch requirements," Greaves said.